The invention relates to a method for manufacturing a ceramic filter element which may be used, for example, as an exhaust filter for an internal combustion engine.
Published Japanese patent application no. JP 63134020 A describes a ceramic filter element for an exhaust filter in an internal combustion engine that is constructed from a corrugated, spirally wound filter sheet. To manufacture the filter sheet, heat-resistant inorganic fibers in an aqueous suspension are mixed with ceramic powder and processed into a sheet. Several superimposed sheets are rolled into the desired shape of the filter body, so that honeycomb flow paths are formed between adjacent filter sheets. The filter body is subsequently fired at a high temperature.
A disadvantage in this manufacturing process is that it is relatively costly. In a first process step, a filter sheet must first be produced from the suspension of heat resistant inorganic fibers and the raw ceramic powder. This filter sheet must then be processed into the desired filter shape in a second process step and finally fired in a third process step. A further disadvantage is that the inorganic fibers in the finished filter body can reduce the filtering efficiency.